Donald Trump survived an assassination attempt at a campaign rally in Pennsylvania on Saturday, with footage showing the former US president defiantly raising his fist with blood on his face as he was escorted off the stage by Secret Service agents. The shooting in the town of Butler, north of Pittsburgh, is likely to cause political shockwaves in the United States just months ahead of Trump’s rematch with President Joe Biden in November’s elections. A shooter was able to climb onto the roof of a nearby building and fire a number of bullets at Trump with an assault rifle, causing panic to brea…